Planar element for forming heat exchanger

ABSTRACT

Planar element adapted to form, when stacked with a plurality of other such elements, a heat exchanger, comprising an inlet region, a first zone adapted to direct flow from the inlet region towards a second zone, a second zone comprising at least one cutout in the plane of the planar element, adapted to accommodate a cooling core, a third zone, adapted to direct flow from the second zone towards an outlet region and an outlet region, the planar element comprising a first blockage protrusion disposed along a first group of said side edges, the first group comprising at least a side edge adjacent to said outlet region, and a second blockage protrusion disposed along a second group of said side edges, the second group comprising at least a side edge adjacent to said inlet region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Application No.16/868,560, filed May 7, 2020, which is a continuation of U.S. Pat.Application No. 15/960,550, filed on Apr. 24, 2018, which is acontinuation of U.S. Pat. Application No 14/859,910, filed on Sep. 21,2015, now U.S. Pat. No. 9,976,817, which is a continuation of U.S. Pat.Application No. 13/834,857, filed on Mar. 15, 2013, now U.S. Pat. No.9,140,396, each of which is incorporated by reference in its entiretyherein.

FIELD OF THE INVENTION

The present invention relates to dehumidification generally.

BACKGROUND OF THE INVENTION

Various types of dehumidifiers are known in the art.

SUMMARY OF THE INVENTION

The present invention seeks to provide improved heat exchanger planarelements.

There is thus provided in accordance with a preferred embodiment of thepresent invention planar element adapted to form, when stacked with aplurality of other such elements, a heat exchanger, the planar elementcomprising an inlet region, a first zone adapted to direct flow from theinlet region towards a second zone, a second zone comprising at leastone cutout in the plane of the planar element, adapted to accommodate acooling core, a third zone, adapted to direct flow from the second zonetowards an outlet region and an outlet region. Preferably the perimeterof the planar element comprises side edges.

According to embodiments of the present invention the planar element maycomprise a first blockage protrusion disposed along a first group ofsaid side edges, the first group comprising at least a side edgeadjacent to said outlet region, the first blockage protrusion is adaptedto block flow from said inlet region directly to said outlet region anda second blockage protrusion disposed along a second group of said sideedges, the second group comprising at least a side edge adjacent to saidinlet region, the second blockage protrusion is adapted to block flowfrom said outlet region directly to said inlet region.

According to further embodiments the planar element comprise at leastone first guiding protrusion adapted to guide the airflow within saidfirst region from the inlet region. The planar element may furthercomprise at least one second guiding protrusion adapted to guide theairflow within said third region toward the outlet region.

According to yet further embodiments the planer element may comprise atleast one third protrusion is disposed in said first region and adaptedto keep a defined gap between said planar element and a second planarelement disposed adjacent to the planar element, in the inlet region.

According to further embodiments the planar element may further compriseat least one fourth protrusion is disposed in said third region andadapted to keep a defined gap between said planar element and a secondplanar element disposed adjacent to said planar element, in the outletregion and at least one fifth protrusion disposed around said cutoutadapted to keep a defined gap between said planar element and a secondplanar element disposed adjacent to the planar element, in the cutoutregion.

According to further embodiments the planar element may further compriseat least a first set of relatively parallel protrusions adapted to guidethe airflow within said first region and at least a second set ofrelatively parallel protrusions adapted to guide the airflow within saidthird region.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe drawings in which:

FIGS. 1A and 1B are simplified top view and bottom view pictorialillustrations of a dehumidification apparatus constructed and operativein accordance with a preferred embodiment of the present invention;

FIG. 1C is a simplified exploded view illustration of thedehumidification apparatus of FIGS. 1A & 1B;

FIGS. 2A and 2B are simplified top view and bottom view illustrations ofa base element, forming an optional part of the dehumidificationapparatus of FIGS. 1A-1C;

FIGS. 3A and 3B are exploded view illustrations of a heat exchangeassembly including a cooling core and a core-surrounding air flowpre-cooling and post heating assembly (CSAFPCPHA) constructed andoperative in accordance with first and second preferred embodiments ofthe invention and forming part of the dehumidification apparatus ofFIGS. 1A-1C;

FIGS. 4A and 4B are simplified illustrations of a first end plateelement, forming part of the dehumidification apparatus of FIGS. 1A-1C;

FIGS. 5A and 5B are simplified illustrations of a second end plateelement, forming part of the dehumidification apparatus of FIGS. 1A-1C;

FIGS. 6A and 6B are respective simplified assembled view and explodedview illustrations of a cooling core assembly forming part of the heatexchange assembly of FIG. 3A;

FIGS. 7A and 7B are respective simplified assembled view and explodedview illustrations of a cooling core assembly forming part of the heatexchange assembly of FIG. 3B;

FIGS. 8A and 8B are respective simplified assembled view and explodedview illustrations of a core-surrounding air flow pre-cooling and postheating assembly (CSAFPCPHA) forming part of the heat exchange assemblyof FIGS. 3A & 3B;

FIGS. 9A and 9B are respective simplified plan view and pictorial viewillustrations of a first side of a first plate of the core-surroundingair flow pre-cooling and post heating assembly (CSAFPCPHA);

FIGS. 10A and 10B are respective simplified plan view and pictorial viewillustrations of a second side of a first plate of the core-surroundingair flow pre-cooling and post heating assembly (CSAFPCPHA);

FIGS. 11A and 11B are respective simplified plan view and pictorial viewillustrations of a first side of a second plate of the core-surroundingair flow pre-cooling and post heating assembly (CSAFPCPHA);

FIGS. 12A and 12B are respective simplified plan view and pictorial viewillustrations of a second side of a second plate of the core-surroundingair flow pre-cooling and post heating assembly (CSAFPCPHA);

FIG. 13 is a simplified, partially exploded, pictorial illustration ofpart of the heat exchange assembly of FIGS. 3A and 3B, showing typicalair flows between adjacent embossed generally planar elements; and

FIGS. 14A, 14B, 14C and 14D are simplified illustrations of air flowthrough the heat exchange assembly of FIGS. 3A and 3B, where FIG. 14A isa planar view and FIGS. 14B, 14C and 14D are sectional views taken alongrespective section lines B-B, C-C and D-D in FIG. 14A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention describes apparatus which producesdehumidification and can be embodied in a number of alternativeoperational contexts, such as part of a dehumidification apparatus, anair conditioner or a water generation system providing water fordrinking or any other use. The apparatus described hereinabove normallyrequires an air flow of humid air thereto and a concomitant air pressuregradient thereacross. It also requires provision of a coolant fluid,which may be any suitable gas or liquid.

Reference is now made to FIGS. 1A-3B, which are simplified pictorialillustrations of a dehumidification apparatus 100 constructed andoperative in accordance with a preferred embodiment of the presentinvention. As seen in FIGS. 1A-3B, the dehumidification apparatus 100includes a cooled core 102 coupled to an external cooling source (notshown) via a cooling fluid inlet pipe 104 and a cooling fluid outletpipe 106. The cooling fluid may be any suitable coolant, such as ammoniaor FREON®., which are supplied in a partially liquid phase and change toa gaseous phase in the core 102, or a chilled liquid, typically water oralcohol, which remains throughout in a liquid phase.

At least first and second relatively humid air inlet pathways 108 leadto the cooled core 102 and at least first and second relatively dry airoutlet pathways 112 extend from the cooled core 102.

In accordance with a preferred embodiment of the present invention,there is provided a core-surrounding air flow pre-cooling and postheating assembly (CSAFPCPHA) 120 wherein the at least first and secondrelatively dry air outlet pathways 112 are in heat exchange propinquitywith respective ones of the at least first and second relatively humidair inlet pathways 108, whereby relatively humid air in the first andsecond relatively humid air inlet pathways is precooled upstream of thecooled core 102 and relatively dry air in the first and secondrelatively dry air outlet pathways is heated downstream of the cooledcore 102.

It is a particular feature of an embodiment of the present inventionthat the cooled core 102 is formed of core elements, such as core plates122, along which an air flow passes, and the at least first and secondrelatively humid air inlet pathways and the at least first and secondrelatively dry air outlet pathways are formed of pathway elements, suchas embossed generally planar elements 124 and 126, along which an airflow passes, the core elements having a relatively high thermalconductivity in a direction along which the air flow passes and thepathway elements having a relatively low thermal conductivity in adirection along which the air flow passes. It is appreciated that coreplates 122 are aligned with and sealed with respect to correspondingplanar elements 124 and 126.

As seen particularly in FIGS. 1A-1C, the dehumidification apparatus 100also preferably includes a base subassembly 130, which provides a sumpfor drainage of condensate, end plate subassemblies 132 and 134, endcover plates 136 and 138, a top air flow sealing plate 140 whichpreferably restricts inlet air flow to be along the passageways 108, apair of bottom air flow sealing plates 142 which preferably restrictoutlet air flow to be along the passageways 112 and a pair of side airflow sealing plates 144, which separate between respective pairs ofinlet and outlet air flow passageways 108 and 112. A circumferentialplate 148, shown here symbolically, separates between an ambientrelatively humid air environment which is maintained at a relativelyhigh pressure and a relatively dry air environment, which is maintainedat a relatively low pressure.

Turning now specifically to FIGS. 2A & 2B, which are simplifiedillustrations of a base subassembly forming an optional part of thedehumidification apparatus of FIGS. 1A & 1B, it is seen that the basesubassembly is typically welded of sheet metal and includes a pair ofmutually inclined plates 160 and 162 which are joined by a pair of endportions 164 and 166 which define legs 168. A pair of sump apertures 170are preferably formed at opposite ends of the junction of plates 160 and162 and are preferably fitted with respective sump pipes 174.

Turning now to FIGS. 3A and 6A & 6B, it is noted that these drawingsillustrate a heat exchange assembly including a cooling core 102 and acore-surrounding air flow pre-cooling and post heating assembly(CSAFPCPHA) 120 particularly suited for use with a gaseous coolant, suchas FREON.RTM., and accordingly coolant piping 180 is preferably providedwith a distributor 182, which divides a flow of gas into multipleseparate flows, each of which passes through a separate gas circulationpathway.

Turning now to FIGS. 3B and 7A & 7B, it is noted that these drawingsillustrate a heat exchange assembly including a cooling core 102 and acore-surrounding air flow pre-cooling and post heating assembly(CSAFPCPHA) 120 particularly suited for use with a liquid coolant, suchas chilled water or alcohol, and accordingly coolant piping 190 ispreferably provided without a distributor 182.

Reference is now made to FIGS. 4A & 4B, which illustrate end plate 132.It is seen that end plate 132 comprises a generally planar portion 202having an array of apertures 204 arranged to accommodate coolant piping,such as piping 180 or 190, and preferably includes a plurality of bentover edges 206 and a plurality of double bent over edges 208 onto whichend cover plate 136 may be sealingly attached.

Reference is now made to FIGS. 5A & 5B, which illustrate end plate 134.It is seen that end plate 134 comprises a generally planar portion 222having an array of apertures 224 arranged to accommodate coolant piping,such as piping 180 or 190, and preferably includes a plurality of bentover edges 226 and a plurality of double bent over edges 228 onto whichend cover plate 138 may be attached. It is noted that one of bent overedges 226 is preferably formed with an aperture 230 which accommodatescooling fluid inlet pipe 104 and cooling fluid outlet pipe 106.

Reference is now made to FIGS. 8A-12B, which illustrate the structure ofthe core-surrounding air flow pre-cooling and post heating assembly(CSAFPCPHA). As seen in FIGS. 8A & 8B, the CSAFPCPHA is made up of astack of two different embossed generally planar elements 124 and 126which are preferably arranged in mutually interdigitated touchingrelationship with each other about the core 102.

The structure and operation of embossed generally planar elements 124and 126 will now be described with specific reference to FIGS. 9A-12B.It is noted that planar elements 124 and 126 are preferably formed byconventional vacuum forming techniques from relatively non-conductiveflexible material, typically plastic, such as PVC and PET, typically ofthickness 0.3 mm.

Turning first to generally planar element 124, a first side thereof,designated by reference numeral 300, is shown in FIGS. 9A and 9B and asecond side thereof, designated by reference numeral 302, is shown inFIGS. 10A and 10B. Planar element 124 preferably has ten side edges,which are designated, clockwise with reference to FIG. 9A, by referencenumerals 320, 321, 322, 323, 324, 325, 326, 327, 328 and 329. Planarelement 124 is formed with a number of protrusions, which extend abovethe plane, designated by reference numeral 330, of planar element 124,in the sense of FIG. 9A, to a height of approximately 3 mm and whichwill now be described in detail. Due to manufacture of planar elements124 and 126 by vacuum forming, there are recesses which correspond witheach of the protrusions.

As seen in FIGS. 9A & 9B, a first side 300 of planar element 124includes an air flow blockage protrusion 340, which extends clockwise inthe sense of FIG. 9A, at first narrowly, from a location near thejunction of edges 320 and 329, along and slightly spaced from edge 320where it becomes wider and then narrows, and narrowly along and spacedfrom edges 321 and 322. Protrusion 340 serves to prevent air flow aboveplane 330 via edges 320, 321 and 322. Planar element 124 also includesan air flow blockage protrusion 342, which extends clockwise in thesense of FIG. 9A, narrowly, from a location near the junction of edges325 and 326 and along and slightly spaced from edges 326, 327 and 328.Protrusion 342 serves to prevent air flow above plane 330 via edges 326,327 and 328. Planar element 124 also includes an air flow blockageprotrusion 344, which extends along and slightly spaced from edge 324.Protrusion 344 serves to prevent air flow above plane 330 via edge 324.

Planar element 124 also includes, at first side 300, an air flow guidingprotrusion 346 at what is typically an inlet region 348 above plane 330and an air flow guiding protrusion 350 at what is typically an outletregion 352 above plane 330.

Planar element 124 also includes, at first side 300, an array 360 ofmutually spaced enhanced counter flow heat exchange (ECFHE) protrusions362 downstream of inlet region 348. Each of mutually spaced protrusions362 preferably has a tapered inlet end 364 and a tapered outlet end 366.

Planar element 124 also includes, at first side 300, an array 370 ofmutually spaced enhanced counter flow heat exchange (ECFHE) protrusions372 upstream of outlet region 352. Each of mutually spaced protrusions372 preferably has a tapered inlet end 374 and a tapered outlet end 376.

Planar element 124 also includes, at first side 300, a plurality ofmutual inner edge spacing protrusions 380 preferably arranged at thesides of a generally rectangular cutout 382 which accommodates core 102.

Planar element 124 also includes, at first side 300, a plurality ofmutual outer edge spacing protrusions 390 preferably arranged alongedges 323 and 329.

As seen in FIGS. 10A & 10B, second side 302 of planar element 124includes a recess 440, which extends counterclockwise in the sense ofFIG. 10A, at first narrowly, from a location near the junction of edges320 and 329, along and slightly spaced from edge 320, where it becomeswider and then narrows, and narrowly along and spaced from edges 321 and322. Planar element 124 also includes a recess 442, which extendscounterclockwise in the sense of FIG. 10A, narrowly, from a locationnear the junction of edges 325 and 326 and along and slightly spacedfrom edges 326, 327 and 328. Planar element 124 also includes a recess444, which extends along and slightly spaced from edge 324. Recesses440, 442 and 444 cooperate with corresponding protrusions on planarelement 126 to provide enhanced registration of the stack ofinterdigitated planar elements 124 and 126.

Planar element 124 also typically includes, at second side 302, a recess446 at inlet region 348 and a recess 450 at outlet region 352.

Planar element 124 also includes, at second side 302, an array 460 ofmutually spaced enhanced counter flow heat exchange (ECFHE) recesses 462downstream of inlet region 448. Each of mutually spaced recesses 462preferably has a tapered inlet end 464 and a tapered outlet end 466.

Planar element 124 also includes, at second side 302, an array 470 ofmutually spaced enhanced counter flow heat exchange (ECFHE) recesses 472upstream of outlet region 352. Each of mutually spaced recesses 472preferably has a tapered inlet end 474 and a tapered outlet end 476.

Planar element 124 also includes, at second side 302, a plurality ofmutual inner edge spacing recesses 480 preferably arranged at the sidesof generally rectangular cutout 382 which accommodates core 102.

Planar element 124 also includes, at second side 302, a plurality ofouter edge recesses 490 preferably arranged along edges 323 and 329.

Turning now to generally planar element 126, a first side thereof,designated by reference numeral 500, is shown in FIGS. 11A and 11B and asecond side thereof, designated by reference numeral 502, is shown inFIGS. 12A and 12B. Planar element 126 preferably has ten side edges,which are designated, counterclockwise with reference to FIG. 11A, byreference numerals 520, 521, 522, 523, 524, 525, 526, 527, 528 and 529.Planar element 126 is formed with a number of protrusions, which extendabove the plane, designated by reference numeral 530, of planar element126, in the sense of FIG. 11A, to a height of approximately 3 mm andwhich will now be described in detail. Due to manufacture of planarelements 124 and 126 by vacuum forming, there are recesses whichcorrespond with each of the protrusions.

As seen in FIGS. 11A & 11B, first side 500 of planar element 126includes an air flow blockage protrusion 540, which extendscounterclockwise, in the sense of FIG. 11A, at first narrowly, from alocation near the junction of edges 520 and 529, along and slightlyspaced from edge 520 where it becomes wider and then narrows, andnarrowly along and spaced from edges 521 and 522. Protrusion 540 servesto prevent air flow above plane 530 via edges 520, 521 and 522. Planarelement 126 also includes an air flow blockage protrusion 542, whichextends counterclockwise, in the sense of FIG. 11A, narrowly, from alocation near the junction of edges 525 and 526 and along and slightlyspaced from edges 526, 527 and 528. Protrusion 542 serves to prevent airflow above plane 530 via edges 526, 527 and 528. Planar element 126 alsoincludes an air flow blockage protrusion 544, which extends along andslightly spaced from edge 524. Protrusion 544 serves to prevent air flowabove plane 530 via edge 524.

Planar element 126 also includes, at first side 500, an air flow guidingprotrusion 546 at what is typically an inlet region 548 above plane 530and an air flow guiding protrusion 550 at what is typically an outletregion 552 above plane 530.

Planar element 126 also includes, at first side 500, an array 560 ofmutually spaced enhanced counter flow heat exchange (ECFHE) protrusions562 downstream of inlet region 548. Each of mutually spaced protrusions562 preferably has a tapered inlet end 564 and a tapered outlet end 566.

Planar element 126 also includes at first side 500, an array 570 ofmutually spaced enhanced counter flow heat exchange (ECFHE) protrusions572 upstream of outlet region 552. Each of mutually spaced protrusions572 preferably has a tapered inlet end 574 and a tapered outlet end 576.

Planar element 126 also includes, at first side 500, a plurality ofmutual inner edge spacing protrusions 580 preferably arranged at thesides of a generally rectangular cutout 582 which accommodates core 102.

Planar element 126 also includes, at first side 500, a plurality ofmutual outer edge spacing protrusions 590 preferably arranged alongedges 523 and 529.

As seen in FIGS. 12A & 12B, second side 502 of planar element 126includes a recess 640, which extends clockwise in the sense of FIG. 12A,at first narrowly, from a location near the junction of edges 520 and529, along and slightly spaced from edge 520 where it becomes wider andthen narrows, and narrowly along and spaced from edges 521 and 522.Planar element 126 also includes a recess 642, which extends clockwisein the sense of FIG. 12A, narrowly, from a location near the junction ofedges 525 and 526 and along and slightly spaced from edges 526, 527 and528. Planar element 126 also includes a recess 644, which extends alongand slightly spaced from edge 524. Recesses 640, 642 and 644 cooperatewith corresponding protrusions on planar element 124 to provide enhancedregistration of the stack of interdigitated planar elements 124 and 126.

Planar element 126 also typically includes, at second side 502, a recess646 at inlet region 548 and a recess 650 at outlet region 552.

Planar element 126 also includes, at second side 502, an array 660 ofmutually spaced enhanced counter flow heat exchange (ECFHE) recesses 662downstream of inlet region 548. Each of mutually spaced recesses 662preferably has a tapered inlet end 664 and a tapered outlet end 666.

Planar element 126 also includes, at second side 502, an array 670 ofmutually spaced enhanced counter flow heat exchange (ECFHE) recesses 672upstream of outlet region 552. Each of mutually spaced recesses 672preferably has a tapered inlet end 674 and a tapered outlet end 676.

Planar element 126 also includes, at second side 502, a plurality ofmutual inner edge spacing recesses 680 preferably arranged at the sidesof generally rectangular cutout 582 which accommodates core 102.

Planar element 126 also includes, at second side 502, a plurality ofouter edge recesses 690 preferably arranged along edges 523 and 529.

Reference is now made to FIG. 13 , which is a simplified partiallyexploded, pictorial illustration of part of the heat exchange assemblyof FIGS. 3A and 3B, showing typical air flows between adjacent embossedgenerally planar elements and to FIGS. 14A, 14B, 14C and 14D, which aresimplified illustrations of air flow through the heat exchange assemblyof FIGS. 3A and 3B, where FIG. 14A is a planar view and FIGS. 14B, 14Cand 14D are sectional views taken along respective section lines B-B,C-C and D-D in FIG. 14A.

FIG. 13 shows airflow, designated generally by reference numeral 700,between a first side 300 of a planar element 124 and a second side 502of a planar element 126. The second side 502 of planar element 126 isnot seen in FIG. 13 . FIG. 13 also shows airflow, designated generallyby reference numeral 702, between a first side 500 of a planar element126 and a second side 302 of a planar element 124. The second side 302of planar element 124 is not seen in FIG. 13 .

Considering airflow 700, it is seen that a relatively planar flow oftypically relatively humid air enters at an inlet region 348 above theplane 330 of planar element 124, and which is bounded by adjacent secondside 502 of planar element 126. This flow is guided by one or moreprotrusions 346 into engagement with array 360 of protrusions 362 onplanar element 124 and corresponding positioned array 670 of recesses672 of planar element 126. It is appreciated that the protrusions 362partially seat within corresponding recesses 672 and together define anair flow passage between each recess 672 and the correspondingprotrusion 362 partially seated therewithin. It is noted that thetapered ends 364 and 366 of the protrusions 362 and the tapered ends 674and 676 of recesses 672 assist in defining these air flow passages.

Downstream of arrays 360, the air flow, which by this stage has beensomewhat pre-cooled, as will be described hereinbelow, passes throughthe core plates 122 of core 102 in a generally planar flow, where it issubstantially cooled, preferably to below the dew point. Downstream ofcore plates 122 of core 102, the substantially cooled air flow passesthrough array 370 of protrusions 372 on planar element 124 andcorresponding positioned array 660 of recesses 662 on planar element126. It is appreciated that the protrusions 372 partially seat withincorresponding recesses 662 and together define an air flow passagebetween each recess 662 and the corresponding protrusion 372 partiallyseated therewithin. It is noted that the tapered ends 374 and 376 of theprotrusions 372 and the tapered ends 664 and 666 of the recesses 662assist in defining these air flow passages.

Downstream of arrays 370, the air flows, which have at this stage beensomewhat warmed, as will be described hereinbelow, become joined into arelatively planar flow at outlet region 352 above the plane 330 ofplanar element 124, and which is bounded by adjacent second side 502 ofplanar element 126. This flow is guided by one or more protrusions 350.

Considering airflow 702, it is seen that a relatively planar flow oftypically relatively humid air enters at an inlet region 548 above theplane 530 of planar element 126, and which is bounded by adjacent secondside 302 of planar element 124. This flow is guided by one or moreprotrusions 546 into engagement with array 560 of protrusions 562 onplanar element 126 and corresponding positioned array 470 of recesses472 on planar element 124. It is appreciated that the protrusions 562partially seat within corresponding recesses 472 and together define anair flow passage between each recess 472 and the correspondingprotrusion 562 partially seated therewithin. It is noted that thetapered ends 564 and 566 of the protrusions 562 and the tapered ends 474and 476 of the recesses 472 assist in defining these air flow passages.

Downstream of arrays 560, the air flow, which by this stage has beensomewhat pre-cooled, as will be described hereinbelow, passes throughthe core plates 122 of core 102 in a generally planar flow, where it issubstantially cooled, preferably to below the dew point. Downstream ofcore plates 122 of core 102, the substantially cooled air flow passesthrough array 570 of protrusions 572 on planar element 126 andcorresponding positioned array 460 of recesses 462 on planar element124. It is appreciated that the protrusions 572 partially seat withincorresponding recesses 462 and together define an air flow passagebetween each recess 462 and the corresponding protrusion 572 partiallyseated therewithin. It is noted that the tapered ends 574 and 576 of theprotrusions 572 and the tapered ends 464 and 466 of the recesses 462assist in defining these air flow passages.

Downstream of arrays 570, the air flows, which have at this stage beensomewhat warmed, as will be described hereinbelow, become joined into arelatively planar flow at outlet region 552 above the plane 530 ofplanar element 126, and which is bounded by adjacent second side 302 ofplanar element 124. This flow is guided by one or more protrusions 550.

Referring additionally to FIGS. 14A-14D, it is seen that the air flows700 and 702 between adjacent partially interdigitated planar elements124 and 126 in the stack are in a generally counter flow mutual heatexchanging relationship, notwithstanding that the air flows are notentirely parallel, particularly at their respective inlet and outletregions. It is an important feature of the invention that the air flows700 and 702 are generally parallel in two dimensions as they passthrough the core 102 and are generally parallel in three dimensions asthey pass through the air flow passages defined between the protrusionsand recesses of arrays 360 and 570 respectively and as they pass throughthe air flow passages defined between the protrusions and recesses ofarrays 370 and 560 respectively.

Thus it may be appreciated that enhanced heat exchange is providedbetween mutually counter airflows in the air flow passages definedbetween the protrusions and recesses of arrays 360 and 670 respectivelyand as they pass through the air flow passages defined between theprotrusions and recesses of arrays 570 and 460 respectively, whereinthree-dimensional counter flow is provided, and a lesser degree of heatexchange is provided therebetween in the inlet and outlet regionswherein only two-dimensional heat exchange engagement between adjacentplanar air flows is provided.

This can be seen graphically from a comparison of FIGS. 14B and 14C.FIG. 14B shows a two-dimensional counter flow heat exchange relationshipbetween adjacent generally planar air flows in the core 102 betweenadjacent plates 122 of the core 102.

FIG. 14C shows a three-dimensional counter flow heat exchangerelationship between adjacent generally planar air flows along the flowpaths defined by arrays 360 and 670. FIG. 14C also represents thethree-dimensional counter flow heat exchange relationship betweenadjacent generally planar air flows along the flow paths defined byarrays 570 and 460.

It is appreciated that the heat exchange relationship represented inFIG. 14C is greatly enhanced as compared with that represented in FIG.14B by virtue of the fact that nearly each flow shown in FIG. 14C issurrounded on four sides by a counterflowing flow path, whereas in FIG.14B, nearly each planar flow is surrounded on two sides by acounterflowing flow path. It is further appreciated that the protrusionsand recesses defining the flow paths are downwardly inclined so toenhance ease of draining of condensate therefrom via edges 325 and 525into base subassembly 130 for drainage and preferably utilization asdrinking water.

Realization of the highly efficient heat exchange structure shown inFIG. 14C is achieved in accordance with a particular feature of thepresent invention by the partial interdigitization of the protrusionsand recesses described hereinabove and visualized in FIG. 14D, whichshows the arrangement of these flow paths in a view taken perpendicularto the planes 330 and 530 of the respective planar elements 124 and 126.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the invention includes bothcombinations and subcombinations of the various features describedhereinabove as well as modifications and variations thereof which wouldoccur to persons skilled in the art upon reading the foregoingdescription and which are not in the prior art.

1. A planar element for forming, in combination with other planarelements assembled in a stack, a heat exchanger, said planar elementcomprising: an inlet region and an outlet region a first array ofmutually spaced enhanced counter flow heat exchange (ECFHE) protrusionsdownstream of said inlet region of said planar element; and a secondarray of mutually spaced enhanced counter flow heat exchange (ECFHE)protrusions upstream of said outlet region of said planar element. 2.The planar element according to claim 1, wherein each of said mutuallyspaced protrusions of said first array and/or of said second array has atapered inlet end and a tapered outlet end.